1581916 has 24 divisors (see below), whose sum is σ = 3231200. Its totient is φ = 677376.

The previous prime is 1581911. The next prime is 1581919. The reversal of 1581916 is 6191851.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 796 + ... + 1948.

2^1581916 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1581916, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1615600).

1581916 is an abundant number, since it is smaller than the sum of its proper divisors (1649284).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1581916 is a wasteful number, since it uses less digits than its factorization.

1581916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1178 (or 1162 counting only the distinct ones).

The product of its digits is 2160, while the sum is 31.

The square root of 1581916 is about 1257.7424219609. The cubic root of 1581916 is about 116.5183894049.

The spelling of 1581916 in words is "one million, five hundred eighty-one thousand, nine hundred sixteen".